Honors College Capstone Experience/Thesis Projects



Document Type



Silver (Hypopthalmichthys molitrix) and bighead (H. nobilis) carp, are invasive species that have negative impacts upon ecosystems. H. molitrix is known to jump completely out of the water in response to broadband sounds, however, this is not observed in H. nobilis. Preliminary experiments reveal that sounds can be used to modify the behavior of carps. Thus, understanding the hearing abilities of these species is important in order to design appropriate acoustical deterrents. Fish heads were preserved in 4% paraformaldehyde and the inner ears dissected and photographed under a light microscope in order to describe the general structure of the ear, which have never been previously described. In addition, some of the ears were processed further, with the sensory epithelia trimmed, and then stained with phalloidin and DAPI, and examined under an epiflourescence microscope. For saccules, hair cell counts were performed in nine 2500 μm2 locations across the epithelia from rostral to caudal ends. Both species had similar patterns of hair cell densities, with the mean (±SE) number of hair cells found centrally being the least (33.7±3.9 for H. molitrix, 32.1±1.4 for H. nobilis), and greatest densities found caudally (71.3±7.7 for H. molitrix, 75.6±4.8 for H. nobilis). At the 55% and 65% locations along the rostral-caudal axis of the saccule, H. molitrix had significantly more hair cells than H. nobilis. The increased hair cell density in the central saccule of H. molitrix may explain why this species is more behaviorally responsive to broadband sounds.

Advisor(s) or Committee Chair

Michael Smith, Ph.D.


Biology | Other Animal Sciences | Other Ecology and Evolutionary Biology